What types of data can be effectively indexed in database management systems?

The following types of data are efficiently indexed in database management systems (DBMS):

• Numeric types (integer, float) — allow for fast comparisons and range queries.
• String types (varchar, text) — especially when using prefix or full-text indexes.
• Dates and times — for quick searches over time ranges.
• Boolean values — although indexing may be less effective with low selectivity.
• Geographical data — using special spatial indexes (e.g., R-trees).

It is important to note that indexes are most effective when the data has high selectivity, meaning queries using the index significantly reduce the number of records processed.

Example: an index on the email field in a users table will speed up searching for a specific user by email.